Numerous devices collect, process, and/or present information to a human user. When the user needs to comprehend only a small amount of information, simple textual and numeric displays may be adequate. However, when a large amount of information is to be presented to the user, when the information may include more complex relationships that the user needs to comprehend, and when the user needs to fully grasp the presented information and its relationships quickly, then displays which present only text and numbers are inadequate. In these situations graphic displays are desirable because graphics typically enhance a user's ability to quickly appreciate the nature of the information being presented. The use of radar display terminals, oscilloscopes and spectrum analyzers are a few examples of situations which depict information graphically.
Current practical displays are limited to the use of only two dimensions for displaying graphic information. Consequently, information characterized by two independent variables is easily accommodated, and even information characterized by three independent variables may be accommodated through the use of projection views determined by trigonometric calculations. However, problems arise when more than three independent variables are required to present information to a user, and the conveyance of information typically suffers.
Unfortunately, certain information presentation situations require the graphic depiction of variations in four or five independent variables. These situations occur, for example, when two independent parameters, such as latitude and longitude, amplitude and frequency, or the like, vary in time and in accordance with another parameter. The other parameter may, for example, describe a particular one of several different sensors or other measuring devices that are used to collect signals describing the two independent parameters.
The information presentation problem becomes more complex when signal or data quality is to be depicted as well. The depiction of signal or data quality is useful to distinguish between an absence of valid data and the presence of valid data which indicate an absence of signal. For example, a user to whom information is being presented may notice that a previously visible graphic object is no longer being displayed. The graphic object's disappearance may be attributed to an absence of the real world phenomenon being measured or to an absence of signals characterizing the real world phenomenon.